Exhaust fan automatic shutter



March 17, 1953 V. E. SPROUSE ET AL EXHAUST FAN AUTOMATIC SHUTTER Filed Dec. 20, 1949 5 Sheets-Sheet l INVEN ToRs, VERNER E. SPRousE AND TRUEMAN P JORDAN, By MQ, m,

d-TTORNEY.

March 17, 1953 v, E. SPROUSE ET AL EXHAUST FAN AUTOMATIC SHUTTER Filed Dec. 20, 1949'v 3 Sheets-Sheet 2 NHKQ INV/5N Tons,

M m T MQH Illi i I I D N A E s U 0 R D' 5 E R E N M V March 17, 1953 v, E. SPROUSE ET Al. 2,631,519

EXHAUST FAN AUTOMATIC SHUTTER.

Patented Mar. 17, 195.3

EXHAUST FAN AUTOMATIC SAIP'IUT'1-EYR Verner E. Sprouse and Trueman P. Jordan, Columbus, Ind., assignors Ato V` E. Spronse Company. Inc., Columbus, Ind .a cslrnoratwl? of Indiana Application December 20, 1949 Serial. NO- :1342055 (Cl. 9s- 116) .4Claims.

Thi-s invention relates to an automatically opening and closing shutter for a Ventilating or exhaust fan. A primary purpose of the invention is to provide a shutter construction which, automatically opening under pressure of air delivered from the fan, will open to give an absolutely clear area over the full cross-sectional air ow, at least equal to the diameter of the vfan itsel.

Heretofore, transverse louvers have been ernployed in such manner that while they open automatically upon air flow, thelou-vers are extended across the air flow and therefore offer considerable resistance to that flow and actually cut down the effectiveness of the fan. Moreover such louvers have developed fluttering withconsequent noise and rattle particularly after a short period of usage.

A further primary object of the invention is to provide a structure Which will be absolutely quiet in operation. YThe invention provides a means of eliminating the yconventional type of plenum chamber, and it permits a great lowering of the cost of installation. f

One of the primary features of the invention resides inthe fact that :there farefbut two doors or shutters employed, and .ea-eh of these shutters are hinged at opposite sides to approach a `common meeting line across `the delivery side Aof the ian, andthe mounting is such that when these two shutters approach ltheir full lopened positions, .they are substantially :balanced upon their hinge axes. `-These shutters are opened automatically by pressure of `air generated 'by fthe fan, and they are closed beginning initially with spring urging, andcOmpleting the closing operation under the vinfluence of gravity.

Qne particular form of Vthe invention -is Vherein illustrated and described as being applied -to -a mounting wherein rthe .air ow is in a general vertical direction. This particular flow is that which :would be had when the entire structure to be described is mounted over a hatohway such as would be `presented `in vexhausting air from a room, throughjtheceiling,rand-into-the attic.

AReferring to the drawings,

Fig. 1 is a top plan -view 1in partial section kof a structure embodying the invention;

Fig.i2 is anendlelevationalview-inpartial section;

Fig. 3 is a sidefelevationalview;

Fig. 4, a detail on .an enlargedscale in section on the line;4`4:in.-`Fig. l and The same general vfan housing and mounting structure as herein shown is shown and described in our application led December 20, 1949, Serial No. 134,054,` for Ventilating Fan Mounting Structure, now Patent Number 2,573,145. In the essential .details for the purpose of explainingithe .present invention, there is a rectangular box "general-ly designated by .the numeral lil which .is open from the underside to have the lower edge portion Il surround a natchway.' l

There is a Venturi member I6 extending across the inside of'the structure rI0y to `be mounted' in any suitable sound insulatingmanner'on the box It, such as is described and shown in the copending application.` vA fan generally designa-ted by' the numeral I3 is mounted to revolve on a vertically disposed shaft I4, Aand ythe fan I3 is mounted to extend partially at least `into the opening vI 5 of the Venturimember I6, the upper Adischarge end of this member Hi being adjacent the top edge portion of theboxmember i0.

Across the top side of the box I0, otherwise normally open, areA a pair vof Shutters l'l Vand I8. These shutters -l1 I34 when placed over the top side of the box 'll-Dfhave their opposing edges `|9 and '20 ,brought substantially into contact one `,with the other across a" centrally disposed line 2l v t'v`lj1-i-c'l1 `would"i ntersect the ex- {tended axis of the shaft 141,4. The marginal portions of these shntters Il and i8 willexte'nd'over the top edge portion '2? of the box lll, Fig. 1, a distance, and k the outer vedge portions of these two shutters jljl and [8 are provided respectively with downwardly turned flanges k2? and 24, each extendingvfrom the line w21 on the three remain,- ing edgeportions of those shutters. yAs indicated primarily in Fis 1, these rangs 23 arid l24 are in .spaced relation' frQm 'the marginal @des pdr.,- tion or flange 22 of the box I0. The ,ange 22 constitutes in the Prsent Showing; an outwardly turned flange .extending horizontally from the 'box *It entirely ieereerund Both of thseshlitters l1 .and 1 8 ,are :hinged to the box member u a aienieai-mane. In describing the hinbging connection, reference is made to me ,Shiner 118, @which at' its outer side corners, are ,respecteer .secured ,the hinge lvrewketsi25 @$512.55 Thesebieckets 25 a'ridZfG are identical with theexception `thai-{they} are made in Ightld-.le-bgnd .frls- Beefrne' toAFig. 4, the braclgetg'l consistsof a side leg 2 1 turned at right anglesufrom V-ajluiingle leg 2.8. The upper ends-of'thesejpembfsjland ,287;nt within the downturned flange 24 of theshutter I8 and are secured thereto in any suitable manner such as by welding. With the shutter I8 in its normal, closed position when the fan i3 is inoperative, the leg 2 will extend in vertical parallel and spaced relation from the side of the box ld, and the hinge leg 23 will likewise extend downwardly in spaced parallel relation from the end of the box I0.

A bracket 29 such as a casting is secured in each instance on the opposite ends of the box I to have a pair of spaced apart fingers 33 and 3I extending therefrom in spaced and parallel relation from and to the ends of the box I3, Fig. 5. These brackets 29 each have mounted between their ngers 3G and 3l a bearing sleeve 32 which has an enlarged central cylindrical portion 3@ against the ends of which the lingers 3@ and 3i bear to have the reduced portions extending from that central portion 3B extend through the iingers 33 and 3 I. A bolt 33 extends axially through the bearing member 32 to compressibly urge the lingers 30 and 3I against that central portion 34, as a means of limiting the spacing to be had between those fingers.

The hinge leg 28 has its lower portion revolubly fitted with a 4running fit over this cylindrical portion 34 and retained thereon by extending between the iingers 30 and 3 I. Thus the brackets supporting the shutter i3 are restrained to rock on the horizontal axes of the bolts 33 in each instance. The shutter I'I is mounted in the same manner.

It is to be noted that the axes of the bolts 33 are spaced a considerable distance downwardly below the top edge portion 22 of the box Iii and also spaced inwardly from the sides thereof. The axes of the bolts 33 are purposely located so that the shutters may be rocked to critical open positions as indicated by dash lines, Fig. 2, in which positions for each shutter, a plane including the center of mass of the shutter and the axis through its supporting bolts 33 is substantially vertically disposed. In these positions, the shutters are practically balanced and have no tendency to rock either to a more fully open position or toward a closed position.

As indicated in Figs. 3 and 4, the lower edge portions of the bracket legs 2 terminate in a horizontally disposed andoutwardly turned lip 36. This lip 36 is spaced above the common line of the axis of the bolts 33 a distance which will cause the lips 33 to strike against the box Iii when the shutters I'I and I8 are rocked a sucient distance from their closed to fully opened positions. These lips 36 prevent the shutters Il and IB from reaching those open positions whereby they would tend to be such that the shutters would become completely overbalanced and tend to swing outwardly around and downwardly from the sides of the box I. That is, the lips 36 limit the openings of these shutters I'I and I8 to those positions, from which they would normally drop by gravity if released toward the closed positions.

Each shutter Il and I8 has secured to its outer downturned flange portions 23 and 24 one or more springs, herein shown as two each carrying the designated numeral 3l.

A peculiar mounting of these springs 3'! is had in that each one is positioned by being interconnected by one end to the box top edge portion 22 at a position longitudinally spaced from its other end which is connected to the flange 23 or 24 as the case may be. This mounting results in holding the springs 3'! clear from overlapping on the box edge portion 22 when the shutters Il and I3 approach and reach their closed positions. The springs 31, with the shutters I'I and I8 closed, lie parallel to and between the flanges 23 and 24- and under the edge portion 22. In these closed shutter positions, the springs 31 are under just enough tension to keep them from bowing from their axial straight line conditions and rattling, and in any levent immediately resisting under slight tension, the opening of the shutters.

This initial tensioning of the springs 31 may be variably had and xed by providing an L- shaped tab 4I having atop leg 42 resting on the top side of the box edge portion 22, from which leg 42 a second leg i3 turns downwardly through a slot 44 in the portion 22; nxing the leg i2 to the portion 22 at the desired position such as by welding; vand hooking the spring 3l to the downturned leg 43; Figs. 1 and 4. The variation in spring tension is secured by selective engagement of the spring 3l in any one of the shutter iiange holes 31a.

Preferably Athese springs 3l are spaced apart to be adjacent the downturned bracket legs '21, Fig. 3. Furthermore, the shutters il and I3 would normally tend -to remain in their fully open positions when the lips 3G strike and rest against the sides of the box Iii. This is prevented however by reason of the light and yielding pull of these springs 3l which are then in diagonally, extended positions.

When the shutters II and |18 lare rocked from those upper and fully opened positions, and the centers of mass of the shutters I'I and I8 are carri-ed past xthe vertical planes through the bolts 33, the springs 3'! continue to exert a slight increasing pull on the shutters resisting further opening of the .shutters I1 [and I8 as they might otherwise tend to rtip past those planes out of the path of the current of the delivered air. By `reason of the mounting of vthe springs 3?! to provide diagonal pulls on the shutter flanges '23 `and 2'4 in their open positions, the pull or" the springs does not increase a-t t-he same rate as it otherwise would if the springs operated with their pull entirely normal to the axes of rotation. By this diagonal pull-means, the spring .action is held down to a minimum in the initial shutter opening and is increased rapidly at 'the shutter positions tending to be removed from the pressure of the delivered air current.

Starting with the shutters Il and I8 in their closed positions, Fig. l, and the fan I3 inoperative, the entire area across lthe opening of the box Iii and primarily across the opening Il5 of the Venturi-plate IS will be -closed off by the shutter-s II and I8 against the i-o-w of any air therethrough, particularly @from the t-opside downwardly, and likewise dust, foreign matter, and insects will be prevented from travelling downwardly through the box Iii lfrom the upper side thereof by reason of the closure of those shutters Il and I-8.

yWhen the fan I3 is set into operation to discharge a Icolumn -o-f air upwardly from the Venu turi member I6 through the opening I5, pressure is then generated immediately against the undersides of the shutters II and I8. As the pressure is built up, the shutters Il' and t8 will start to lrock `about their hinged axes defined by the lines through the Ibolts 313 in each instance. The shutters I? and I8 will rock to their open positions, Ibringing the s-top lips 36 close to their limiting degrees of travel against the sidesof the box I0, with that travel being graduallybraked .by Irea-- son of the increasing resistance of the springs 31 of these springs 3l. However initially under the inertia effect oi' shutter travel, they will swing quite close to the box, and then be rocked outwardly therefrom to some such positions as indicated in Fig. 4, so that there will be no :bump-ing action of these lip portions 3-6 against the box when the device is in operation. The shutters I'I and I8 being divided across the central line ZI will be swung to their open positions as indicated by the dash lines in Fig. 2, so that the edges I9 and 29 will be completely at the outside edge of the column of air being forced upwardly from the fan I3 from Ithe Venturi member lr6, thereby ybeing .completely removed from the cent-ral area of that column of air, and thus offering no resistance directly thereacross.

When the fan I3 is to 'be de-energized, the fan I3 will under the stored up inertia eiect slow down gradually, and as it slows down, the air pressure directed toward the shutters II and I8 will likewise diminish, and under the influence of gravity aided by the springs 31, the shutters Il and I 8 will swing downwardly in accordance with that -diminishing pressure, .and come to rest in their closed positions over the box l0. As indicated in Fig. 2, bumpers 49 made out of any suitable resilient material such as felt or rubber may be positioned to interv-ene between the shutters I7 and I8 adjacent the dividing line 2I so as to cushion the fall of the shutters I .and I 8 as they rea-ch the positions where Ithe air pressure will no longer support them, and they will drop accordingly. The bumpers `40 are provided simply to Iremove the noise ythat might be occasioned in that slight degree of travel at the end of -th-e operation.

Thus it is to be seen that we have lprovided a structure wherein there area minimum number of shutters, two at most, operating automatically with the flow of air exhausted from a fan, and also operating so as to be completely removed from any positions transversely across the flow of that air. Furthermore, it is to be seen that the shutters when in their opened positions actually float again-st the pressure .of the air iiow without ybeing permitted to lbang against metallic parts, and are further aided in closing by reason of th-e springs initially starting tha-t closing action, but the springs being substantially reduced in operation and the closing operation confined substan tially -to the action .of gravity in the final ytravel of the shutters.

While we have shown our invention in the one best form as now known to us, it obvious that structural variations may be employed without departing from the spiri-t of the invention, and we therefore do not desire to be limited to that precise form beyond the limitations which may be imposed Iby the following claims.

We claim:

l. Means for automatically opening and closing a fan discharge opening depending upon fan operation, comprising a mounting box bounded by side walls to dene top openings at opposite ends one of said openings being a top opening; a fan mounted within the box to discharge toward said top opening; a pair of shutters dimensioned to lie normally closed across said top opening and meet substantially by free inner edges on a center line thereacross; hinge legs extending from opposite corners of said shutters removed from said meeting line and down along those side walls of the box over which said center line runs; hinge means carried by said side walls interengaging end portions of said legs whereby said shutters may be rocked thereon on a common axis in each instance from said closed positions to open positions whereby a plane through the center of mass of a shutter and said axis may be vertically disposed; stop means carried by said shutters to abut walls of the box in the path of travel of the shutters to open positions, said stop means being located to stop the opening travel of the shutters at approximately those positions where their said free edges are tangential to the perimeter portion of the flow stream from said opening; and spring means interconnecting between said shutters and said box, yieldingly resisting opening travel toward said stop means limiting positions, and holding said free edges against said flow portion to maintain said stop means in normally spaced relation from said walls; said spring means in each instance consisting of at least one tension spring interconnecting by one end with the discharge end ci said box at one point and by its other end at a point along the outer edge portion of a shutter, said two points being spaced apart longitudinally of the shutter whereby the spring lies parallel thereto when the shutter is closed.

2. Means for automatically opening and closing a fan discharge opening in response with air cw therethrough, comprising a fan; a fan discharge box having a top opening bounded by a box edge; a pair of shutters normally lying in substantially horizontal planes and covering said opening, said shutters substantially meeting by inner opposing edges along a center line across the opening; means hingedly mounting said shutters to swing upwardly by their opposing edges from said center line, comprising for each shutter, legs xed to and downwardly turned from the shutter to extend below said box opening edge; hinge pins engaging said legs to define a hinge axis spaced inwardly under and below the outer edge portion of the shutter, said axis being parallel to said center line and being located intermediate the center of mass of the shutter and said outer edge portion when the shutter is in its closed position; said hinge axis being located to permit said shutter in each instance to be shifted under full air discharge conditions to have a plane through said axis and said center of mass vertically disposed with the shutter in a position inclined from the Vertical over said box.

3. Means for automatically opening and closing a fan discharge opening in response with air ow therethrough, comprising a fan; a fan discharge box having a top opening bounded by a box edge; a pair of shutters normally lying in substantially horizontal planes and covering said opening, said shutters substantially meeting by inner opposing edges along a center line across the opening; means hingedly mounting said shutters to swing upwardly by their opposing edges from said center line, comprising for each shutter, legs fixed to and downwardly turned from the shutter to extend below said box opening edge; hinge pins engaging said legs to define a hinge axis spaced inwardly under and below the outer edge portion of the shutter, said axis being parallel to said center line and being located intermediate the center of mass of the shutter and said outer edge portion when the shutter is in its closed position; said hinge axis 'being located to permit said shutter in each instance to be shifted under full air discharge conditions to have a plane through said axis and said center of mass vertically disposed with the shutter in a position inclined from the vertical over said box; stop means limiting opening travel of the shutters to positions between vertical shutter positions and said full air discharge, inclined positions; and spring means resisting travel of the shutters from said inclined positions toward said vertical positions.

4. Means for automatically opening and closing a fan discharge opening in response with air flow therethrough, comprising a fan; a fan discharge box having `a top opening bounded by a box edge; a pair of shutters normally lying in substantially horizontally planes and covering said opening, said shutters substantially meeting by inner opposing edges lalong a center line across the opening; means hingedly mounting said shutters to swing upwardly by their opposing edges from said center line, comprising for each shutter, legs fixed to and downwardlyV turned from the shutter to extend below said box opening edge; hinge pins engaging said legs to define a hinge axis spaced inwardly under and below the outer edge portion of the shutter, said axis being parallel to said center line and being located intermediate the center of mass of the shutter and said outer edge portion when the shutter is in its closed position; said hinge axis being located to permit said shutter in each instance to be shifted under full air discharge conditions to'have a plane through said axis and said center of mass vertically disposed'with the shutter in a position inclined from the vertical over said box; stop means limiting opening travel of the shutters to positions between vertical shutter positions and said full air discharge, inclined positions; and spring means resisting travel of the shutters from said inclined positions toward said vertical positions; said spring means comprising a tension spring for each shutter, one end of the spring being carried by said box, and the other end by said shutter outer edge portion, the axes of the springs being diagonally disposed in reference to said center line by having the spring ends spaced apart longitudinally of the shutters.

VERNER E. SPROUSE. TRUEMAN P. JORDAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,503,915 Posner Aug. A5, 1924 2,295,839 'Grigsby Sept. 15, 1942 2,492,242 Shaver Dec. 27, 1949 FOREIGN PATENTS Number Country Date 14,770 Great Britain July 11, 1908 

